Biomedical subjects

W M Muir

Publications and source records attributed to W M Muir.

At least 37 records · Page 2Linked to original sources

PubMed1991

Selection and beak-trimming effects on behavior, cannibalism, and short-term production traits in White Leghorn pullets.

Pullets of stocks derived from the North Central Randombred White Leghorn population without selection (C) or selected (S) on family performance when kept with beaks intact in multiple-hen cages were compared. Pullets had intact, one-fourth, or one-half of the beak removed (IN, 1/4R, and 1/2R, respectively). No stock differences were detected for behavior traits or other measures during the rearing period. However, beak-trimmed pullets were more inactive and feeding behavior was depressed in 1/2R pullets 1 wk after beak trimming. At 16 wk, 1/4R pullets' beaks had regrown but 1/2R pullets' beaks continued to be shorter than IN pullets' beaks. No differences in fearfulness were found between genetic stocks or among beak length treatments early in the laying period. Deaths from beak-inflicted injuries accumulated steadily from 18 wk until the study was ended at 40 wk. Cannibalistic deaths occurred less frequently in S as compared with C pullets within each beak treatment. As the amount of beak removal increased, beak-inflicted mortality decreased. The S pullets had earlier sexual maturity, lighter egg weights, and greater hen-housed egg production and egg mass than C pullets, and 1/2R pullets had greater egg production than 1/4R and IN pullets. Genetic stock by age and beak treatment by age interactions were present for hen-housed production and egg mass, and the interactions appeared to result primarily from increased mortality from cannibalistic pecking with increased age.

Analysis of Variance↗

PubMed1991

Research note: genetic adaptation to multiple-bird cage environment is less evident with effective beak trimming.

Selection of hens with intact beaks for high performance in multiple-bird cages has produced a stock that clearly exceeds its unselected control when hens have intact beaks but shows less advantage when comparisons involve effectively beak-trimmed birds. The selected stock performed at about the same level as a stock recently derived from a commercial source (but with two generations of relaxed selection) when birds had intact beaks but at a lower level when birds had their beaks trimmed. Relative incidences of deaths from cannibalistic pecking were partially responsible for the results obtained.

Adaptation, Physiological↗

PubMed1987

Multiple vital functions of the daughterless (da) gene in Drosophila melanogaster and factors influencing its expression.

Multiple sub-vital effects, here designated as reductions in fitness S1-S5, for the second chromosome gene 'daughterless' (da) of Drosophila melanogaster were described as (S1) a recessive maternal lethality for daughters, (S2) a reduced fertility of da/da females, (S3) a recessive sub-vital zygotic effect, (S4) a recessive female-specific zygotic effect and (S5) a recessive maternal interaction effect on sons. (For S1-3 see also: Bell, 1954; Sandler, 1972; Cline, 1976). These five distinct effects were initially quantified from estimates of viability in single generation crossing experiments. Dynamic estimates of these fitness parameters were obtained by fitting the elimination rate of da from a series of large random mating cage populations to a recurrence equation by the method of minimum chi-square. The stability of these estimates discerns those effects which are truly pleiotropic versus those due to linked genes. The dynamic estimates supported only S1 and S4 effects. Evidence for S2 and S5 was indeterminate, but the S3 effect was rejected (P less than 0.01). The observed reduction in fitness, supposedly due to this recessive zygotic effect for da, was most likely the result of linked deleterious genes. These results indicate that pleiotropic vital effects observed in single generation test-cross matings may be caused by linked genes rather than the specific mutant per se. This problem is of particular importance when the mutant allele has been maintained with a balancer chromosome. Experiments on the rescue of daughters from da/da mothers with low temperatures during embryogenesis and with dechorionation of eggs were described in which the findings failed to confirm previously reported actions of the da gene. Modifying genes rather than environmental variables were cited as the probable cause for these conflicting results.

Animals↗

PubMed1986

Estimation of response to selection and utilization of control populations for additional information and accuracy.

Problems associated with testing and estimation of response to selection are examined. An alternative procedure with increased power for testing hypotheses is given. The increased power results from a more precise method of estimating the variance about response. The new method is based on a Satterthwaite approximation which combines variance components estimated more precisely by other sources of variation in the analysis of variance. The expected variance about response and expected mean squares for the analysis of variance, used in the Satterthwaite procedure, are given. When intergeneration environmental trends cannot be ruled out, a control population must be used to estimate response to selection. However, if the experimental and control populations do not respond in the same direction and with the same magnitude to common environmental effects, then the usual method of estimating response by deviating the experimental values from the control will result in biased estimates. An alternative procedure, using the control as a covariate to adjust for environmental trends, gives relatively unbiased estimates of response in this situation. Some bias results from measurement error associated with the control. However, this bias is usually minimal.

Analysis of Variance↗

PubMed1985

The effect of dietary cholesterol, energy intake, and oxygen consumption on cholesterol metabolism in the chick.

This experiment, involving 320 chicks, was conducted to determine the effects of dietary cholesterol, restricted caloric intake, and genetic lines on cholesterol metabolism in the bird. The two lines of chicks studied had been divergently selected for oxygen consumption and had been shown to differ significantly (P less than .01) in weight gain and carcass lipid deposition. The dietary treatments, administered for a 2-week period, consisted of two levels of dietary cholesterol (none and supplemented) for each of two levels of energy (ad libitum and restricted). At the end of this 2-week period, the birds were injected intravenously with 1-14C-acetate and their livers removed 4 hr later. Hepatic cholesterol and lipid synthesis were measured by the uptake of acetate. Added dietary cholesterol significantly (P less than .01) decreased hepatic cholesterol synthesis, lipid synthesis, and specific activity of hepatic cholesterol but increased plasma and liver cholesterol. However, the elevation in plasma and liver cholesterol represented only .9 and 1.8% respectively, of the increase in total intake of dietary cholesterol. Metabolizable energy of diets fed ad libitum was also significantly (P less than .01) reduced with supplemented dietary cholesterol. A significant (P less than .01) difference in body weight was present between the two lines, with low oxygen consuming (LOC) birds exhibiting heavier body weights than high oxygen consuming (HOC) birds. A significant interaction between line and energy intake (P less than .05) was present for hepatic cholesterol levels; LOC birds exhibited higher levels of hepatic cholesterol than HOC birds when both groups were fed at restricted levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1984

Cholesterol metabolism in the laying hen as influenced by dietary cholesterol, caloric intake, and genotype.

Three trials, each with 24 hens, were conducted to determine the effects of dietary cholesterol, caloric intake, and genotype on the synthesis, storage, and excretion of cholesterol in the laying hen. The two genotypes of birds used in this experiment had been divergently selected for high and low oxygen consumption and had been shown to differ significantly (P less than .01) in body weight gain and carcass lipid deposition from 0 to 4 weeks of age. The dietary treatment, administered for a 2-week period to birds in each genotype, consisted of two levels of dietary cholesterol (0 and 1% added) and two energy intakes (ad libitum and 75% ad libitum). The experimental design was a 2 X 2 X 2 factorial. One percent added cholesterol versus none supplemented produced a significant (P less than .01) decrease in available metabolizable energy and uptake of acetate into liver cholesterol while causing significant (P less than .01) increases in egg and liver cholesterol but not in plasma cholesterol. Restricting caloric intake, as compared to ad libitum feeding, resulted in significantly (P less than .01) decreased egg production and total amount of cholesterol excreted via the egg with significantly (P less than .05) increased plasma and liver cholesterol levels but no change in egg cholesterol concentration. Differences were significant (P less than .05) between the two genotypes in feed intake and hepatic cholesterol and lipid synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1983

Effect of dietary cholesterol and genotype on cholesterol metabolism in roosters.

An experiment, involving 32 roosters, was designed to study the interaction of dietary cholesterol and genotype on cholesterol metabolism in roosters. The two lines of birds used in this study had been divergently selected for high and low oxygen consumption and had been shown to differ significantly (P less than .01) in body weight gain and carcass lipid deposition from hatch to 4 weeks of age. The dietary treatments, administered for a 2-week period, were 0 and 1% dietary cholesterol added to a basal mash diet. Two separate trials were run, each with 16 roosters, resulting in four replicates of each treatment per line for each trial (block). After the trial period, the birds were injected with 1-(14)C-acetate and livers were removed; hepatic cholesterol synthesis was measured by the uptake of labeled acetate into liver digitonin precipitable sterols. Plasma and liver cholesterol levels were also measured. The data were analyzed as a randomized complete block design. Added dietary cholesterol significantly (P less than .01) increased both plasma and liver cholesterol levels over the control while significantly (P less than .01) decreasing the uptake of acetate into hepatic cholesterol in both lines by about 7-fold. Plasma cholesterol was significantly (P less than .05) greater in the high than low oxygen-consuming birds, and liver cholesterol was higher (P less than .10) in the low than high oxygen-consuming line.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1983

Performance of dwarf and normal laying hens as influenced by protein level and cage density.

The performance of dwarf and normal White Leghorn laying hens with similar genotypes other than for the dwarf gene (dw) was observed over thirteen 28-day periods in a factorial arrangement involving four protein levels (20.0, 18.1, 16.4 or 14.3% protein plus supplemental methionine) and two densities (two or three birds per standard 10 X 16 in cage). The normal birds had significantly higher overall hen-day egg production, egg weight, and body weight, but the dwarf birds excelled for feed efficiency and adult viability. Significant genotype X ration interactions were observed for egg lay, egg weight, body weight, and feed efficiency, primarily due to the relatively poor performance of the dwarf birds on the 14% protein. A significant genotype X density interaction resulted for feed efficiency, due to a higher efficiency in 3-bird than in 2-bird cages for dwarf birds, while the reverse was true for normal birds. These results suggest that the potential of the dwarf gene for increasing the efficiency of commercial egg layers can be enhanced by further study as to optimal nutrition and management regimens.

Animals↗

PubMed1981

Effect of fiber on cholesterol metabolism in the Coturnix quail.

This experiment involving 288 Coturnix quail was conducted to determine the effects of various fiber sources (alfalfa, wheat bran, dried brewer's grain, cellulose, and pectin) on serum, liver and egg yolk cholesterol, and egg production. The fiber sources were added at a rate to provide 6.25% fiber to a corn-soybean meal diet and fed for a 28-day experimental period. Serum, liver, and egg cholesterol levels were measured as pen composite samples at the end of the experimental period. No difference was exhibited in egg yolk cholesterol among any of the groups (P greater than .10). Liver and serum cholesterol levels were elevated in the birds fed the pectin and wheat brain diets as compared with that in birds fed the other fiber source; also, metabolizable energy intakes and eggs per hen day (EHD) were decreased for both groups. When data were adjusted for EHD by covariance analysis, the treatment differences no longer appeared (P greater than .05). These results indicate that 1) there is a basal quantity of cholesterol deposited in the egg on which fiber intake, energy consumed, or egg production have very little effect and that 2) there is an inverse relationship between serum and tissue cholesterol levels and the total quantity of cholesterol excreted via the egg.

Animal Feed↗

PubMed1981

Serum calcium, phosphorus and magnesium responses to massive dosing of cholecalciferol (CC) and 25-OH-CC in young and aged ewes.

Twenty-four ewes were divided into two age groups (one-year-old and nine-year-old) and used to determine the influence of cholecalciferol (CC) and 25-OH-CC on serum concentrations of Ca, P, and Mg with time post-injection. The ewes were maintained in slatted-floor pens and fed 800 g per head daily of a diet which analyzed 0.38% calcium, 0.31% phosphorus, and 0.14% magnesium. This diet was fed throughout the 21-day trial. The ewes were injected on days 0 and 7 as follows: (control) 5 ml ethanol; (CC) 50 mg CC in 5 ml ethanol; and (25-OH-CC) 25 mg 25-OH-CC in ethanol. Blood samples were pre-injection (day 0) and on days 1, 2, 3, 5, 7, 9, 12, 17 and 21 of the trial. Serum Ca averaged 10.81, 11.06 and 11.25 mg/100 ml for the one-year-old ewes and 10.51, 11.06 and 11.54 mg/100 ml for the nine-year-olds across sampling times in groups A to C, respectively. Serum P across sampling times averaged 6.58, 7.80 and 9.51 mg/100 ml in one-year-old ewes and were different (P less than .05) from each other. Serum P averaged 7.06, 8.56 and 8.59 mg/100 ml for the nine-year-old ewes. Serum Mg values were 2.51, 2.32 and 2.19 mg/100 ml for the one-year-old and 2.38, 2.14 and 2.00 mg/100 ml for the nine-year-old ewes across all sampling times for control, CC and 25-OH-CC groups, respectively. Serum Mg in one-year-old ewes was lower (P less than .05) in both CC and 25-OH-CC injected ewes than controls, and was lowest (P less than .05) for 25-OH-CC when compared with the control in nine-year-old ewes. External symptoms of hypervitaminosis (reduced feed intake and leg abnormalities) were apparent after the second injection with 25-OH-CC, and were most pronounced in the aged ewes.

Aging↗

PubMed1980

Feed efficiency and gain responses to protein levels in two lines of birds selected for oxygen consumption.

Two experiments were conducted to investigate the response of two populations of chickens, divergently selected for high and low oxygen consumption, to varying protein levels. Protein levels used for Experiments 1 and 2 were 16, 18, 20, and 22% and 20, 22, 24, and 26%, respectively. The birds were weighed initially and weekly to 4 weeks of age. Feed consumption was ad libitum with amounts consumed recorded weekly. Gross feed efficiency was computed per pen as the difference between initial and weight at 4 weeks divided by feed consumed adjusted for spillage. The results from these experiments indicate that at low protein levels both lines were equally efficient, but, as the level of protein was increased, the low line was increasingly more efficient while the high line became less efficient. Gain for the low O2 birds was greater than the high O2 birds in all cases with both lines increasing in gains equally with increased protein levels.

Animal Feed↗

PubMed1979

Particulate emboli retained by a screen and a depth transfusion filter. A SEM study.

Microembolization by platelet leukocyte aggregates is a threat to the pulmonary microvasculature when blood is transfused to patients. Those aggregates can be removed by filters (either depth filter or screen filter); their efficiency, as shown by SFP measurements is not questionable, however they are working in different ways as observed by SEM: mechanical retention and adsorption.

Animals↗

PubMed1979

Particulate emboli retained by the Intersept (R) transfusion filter; a sem study.

The Intersept (R) transfusion filter is the transfusion filter developed by Johnson and Johnson. Filtration is performed by both adsorption and mechanical retention. Not only microaggregates, but damaged and injured cells are likely to be trapped and/or adsorbed. Such a filter is not injurious to the blood components, but thrombotic material accumulation can occur with fresh blood.

Animals↗

PubMed1974